fix: show saved keys as ready in deployment previews

Replace saved-key inputs with a ready indicator and direct key updates to Keys. Clear hidden key overrides on preview refresh and update the blueprint documentation.

Fixes #41

src/lib/ui/components/DeployServerDialog.svelte

@@ -79,6 +79,7 @@
             if (!res.ok) throw new Error(body.error ?? 'Could not prepare launch preview.');
             if (current === session) {
                 if (previousName && previousName !== body.name) { plutoKey = ''; keyNotice = 'The available server ID changed. Enter the key for the new ID below; the previous key was not transferred.'; }
+                if (body.hasSavedKey) plutoKey = '';
                 preview = body; now = Date.now();
                 await tick(); heading?.focus();
             }
@@ -133,8 +134,9 @@
             </section>
             <form onsubmit={event => { event.preventDefault(); void launch(); }}>
                 <div class="identity"><span class="eyebrow">Your new server</span><strong>{preview.name ?? 'Waiting for an available lobby'}</strong><p>{preview.port ? `Port ${preview.port} · ` : ''}Fresh identity, with its own server key.</p></div>
-                <label>Plutonium server key<input type="password" bind:value={plutoKey} disabled={busy || saving || !preview.name} maxlength="512" autocomplete="off" placeholder={preview.hasSavedKey ? 'Saved key available — leave blank to reuse' : 'Paste the key for this server ID'} /></label>
-                <p class="muted">{preview.hasSavedKey ? 'A key is stored for this exact server ID; its validity is checked when the game starts. Enter a replacement here to update it at launch.' : 'Add the key here. It is saved for this exact server ID when you launch, including if provisioning fails.'} <a href={`/server-keys?server=${encodeURIComponent(preview.name ?? '')}`} target="_blank" rel="noopener">Manage saved keys in a new tab</a>; your launch stays open here.</p>
+                {#if preview.hasSavedKey}<p class="key-ready"><span aria-hidden="true">✓</span> Saved key ready</p>
+                {:else}<label>Plutonium server key<input type="password" bind:value={plutoKey} disabled={busy || saving || !preview.name} maxlength="512" autocomplete="off" placeholder="Paste the key for this server ID" /></label>{/if}
+                <p class="muted">{preview.hasSavedKey ? 'The saved key for this server ID will be reused automatically. Its validity is checked when the game starts. Update it in Keys.' : 'Add the key here. It is saved for this exact server ID when you launch, including if provisioning fails.'} <a href={`/server-keys?server=${encodeURIComponent(preview.name ?? '')}`} target="_blank" rel="noopener">Manage saved keys in a new tab</a>; your launch stays open here.</p>
                 <div class="launch-actions">{#if !sourceDeploymentId}<Button variant="ghost" disabled={busy || saving} onclick={() => { preview = null; plutoKey = ''; error = ''; }}>Back</Button>{/if}<Button type="submit" variant="primary" loading={busy} disabled={busy || saving || expired || !preview.ready || (!preview.hasSavedKey && !plutoKey.trim())}>Launch server</Button></div>
                 {#if !preview.hasSavedKey && !plutoKey.trim()}<p class="muted">Enter this server’s key to enable launch.</p>{/if}
                 <p class="caption">Preview valid until {$timeFormat.minuteTime(preview.expiresAt)}. Lobby and port availability are checked again at launch.</p>
@@ -160,6 +162,7 @@
 <DeployCollectionDialog bind:open={collectionOpen} {blueprintId} />
 
 <style>
+    .key-ready { color: var(--state-online); font-weight: 600; }
     dialog { background: var(--surface); color: var(--text-primary); border: 1px solid var(--border-strong); border-radius: var(--radius-lg); padding: 0; width: min(700px, calc(100vw - 32px)); max-height: calc(100dvh - 40px); }
     dialog::backdrop { background: rgb(0 0 0 / .7); backdrop-filter: blur(5px); }
     .composer { display: grid; gap: 24px; padding: 30px; } header, .section-title { display: flex; justify-content: space-between; align-items: center; gap: 16px; }